1. Field of the Invention
This invention relates generally to a method of remote control and, more particularly, to an interrupt method of remotely controlling the setting of a device, such as a potentiometer in the feedback loop of a preamplifier in an audio mixer.
2. Description of Prior Art
An audio mixer is typically connected to a plurality of microphones and/or other input lines. The microphones and other input lines frequently have a pre-amplifier stage for amplifying the signals before they reach the mixing stages. The pre-amplifiers are generally configured with a potentiometer so that an operator may manually vary the amount of feedback in the pre-amplifier and thus vary the amount of amplification, as is well known in the art.
It is difficult, however, to easily and accurately set the value of the potentiometer to a desired setting, as discussed in U.S. Pat. No. 4,677,674 to Snyder, for example. Snyder discloses a system in which the setting of a fader potentiometer may be reset by the use of test signals and by manually adjusting the potentiometer until the previous setting is reached.
The use of a control system for remotely controlling the setting of a potentiometer is also known. For instance, U.S. Pat. No. 3,831,075 issued to Liska et al. discloses a servo control circuit which has feedback to insure that the desired setting of the potentiometer equals the actual setting of the potentiometer. In this system, an amplifier receives the difference between the actual and desired settings. Depending upon whether this difference is positive or negative, the motor is driven either one or the other directions in order to reposition the potentiometer.
Also, U.S. Pat. No. 4,715,051 issued to Giardina discloses an arrangement which can remotely control the setting of an electronic "potentiometer" having a variable resistance. The arrangement comprises an operator controlled switch which is toggled for causing a counter to either increase or decrease its count. A digital to analog converter receives the output of the counter and transmits an analog signal to a pair of complementary opto-isolators to simulate the effect of a potentiometer. This arrangement replaces the potentiometer with the pair of opto-isolators.
It is a problem in the prior art to remotely control the gain of a pre-amplifier for use with an audio mixer. It is also a problem in the prior art to repeatedly set the value of the potentiometer to a desired value. It is also a problem in the prior art to accurately set the value of a potentiometer.